How often should you run automated tests?

Run fast unit and integration tests on every commit or pull request so feedback arrives in minutes. UI and end-to-end suites are heavier: many teams trigger them on merge to main, nightly, or before release - depending on runtime and infrastructure cost. Critical smoke paths can run on every build; full regression often runs less frequently but before production deploys. The right cadence balances risk, pipeline duration, and flake rate. If a suite takes hours and fails intermittently, developers will skip it - frequency should match reliability. Increase run frequency as stability and parallelization improve, not before.